Control apparatus for a three-dimensional laser working machine and three-dimensional laser working machine

ABSTRACT

The control apparatus for a three dimensional laser working machine teaches a tip position and an attitude of a nozzle and carries out working based on the teaching in a three-dimensional laser working machine having a head structure that a working point does not change when a rotational axis and an attitude axis are rotated. A nozzle direction vector is calculated from current angles of a rotational axis ( 14 ) and an attitude axis ( 16 ). An angle that the attitude axis ( 16 ) changes for constant time is calculated. An angle through which the rotational axis ( 14 ) is to be rotated is calculated so that X and Y directions of the nozzle direction vector are kept constant according to an angle change amount of the attitude axis ( 16 ), and the rotation of the rotational axis ( 14 ) is controlled by the calculated angle.

TECHNICAL FIELD

The present invention relates to a control apparatus for athree-dimensional laser working machine. More specifically, thisinvention relates to a control apparatus for a three-dimensional laserworking machine having a head structure that a working point does notchange when a rotational axis and an attitude axis are rotated, andhaving a unit which teaches a tip position and a directional attitude ofa nozzle.

BACKGROUND ART

As a three-dimensional laser working machine for working a sculpturedsurface, a three-dimensional laser working machine, which has arotational axis (α axis) rotatable around a center axis of a Z axis(vertical axis) and an attitude axis (β axis) rotatable around an axisslanted with respect to the Z axis and has a head structure that whenthe rotational axis and the attitude axis are rotated, a working pointdoes not change, is known (see Japanese Patent Application Laid-Open No.1-162592 (1989)).

FIG. 6 schematically shows the working head having the rotational axis(α axis) and the attitude axis (β axis) In FIG. 6, the working head isshown by a reference numeral 50, and the working head 50 has arotational axis 52, which is rotatable around a center axis of a Z axisby a bearing member 51, at the tip of a Z axis member 60, and anattitude axis 54, which is attached to the tip of the rotational axis 52by a bearing member 53 and is rotatable around an axis slanted withrespect to the Z axis, and a laser nozzle 61 is attached to the tip ofthe attitude axis 54. The working point is shown by a reference symbolN.

In the three-dimensional laser working of a sculptured surface, in orderto maintain an optical axis of a laser emitted to a working surface in anormal direction with respect to the working surface, the laser nozzleis required to be always in an attitude which is orthogonal to theworking surface, and teaching which fulfills this requirement is madeprior to actual working.

There will be explained below an attitude change of the working head atthe time of teaching an attitude change corner section with reference toFIG. 7. In FIG. 7, P₁, P₂ and P₃ show teaching points of a workpiece W.The teaching point P₁ is a teaching point on a horizontal surface, theteaching point P₂ is a teaching point on a 45 degrees slanted surface ofthe workpiece W, and the teaching point P₃ is a teaching point on anupright surface of the workpiece W. The laser nozzle 61 faces justdownward at the teaching point P₁, and is slanted 45 degrees at theteaching point P₂, and faces the horizontal direction at the teachingpoint P₃.

In order to bring the workpiece W into a state orthogonal to theteaching points P₁, P₂ and P₃, it is necessary to change rotating anglesof the rotational axis 52 and the attitude axis 54. For this reason,conventionally in the teaching operation on the attitude change cornersection, an operator rotates the rotational axis 52 and the attitudeaxis 54 every time of the teaching, and brings the laser nozzle 61 intothe orthogonal state with respect to the working surface and makes theteaching.

There will be explained below a procedure of the conventional teachingoperation of the attitude change corner section with reference to FIG.8. Firstly, various setting of a teaching box is carried out, and theteaching operation for teaching working points is brought into astartable state by using a working machine (step S100).

Next, an instruction such as shutter opening of an auxiliary functioncode which is the initial setting in the working program is given, andthe working axis is moved to a teaching point by pushing down a workingaxis feed key which is positioned in the teaching box or by using ahandle or a joy stick and the teaching is made so that respectiveteaching points of the working program are created (step S101). When theteaching points are created, in the conventional teaching operation onthe attitude change corner section, for example in the case of theteaching from the teaching point P₁ on the horizontal surface to theteaching point P₂ on the 45 degrees slanted surface, the working head 50is moved so that a tip coordinate meets the teaching point P₂ on the 45degrees slanted surface (step S102).

Next, the attitude axis 52 and the rotational axis 54 are movedindependently by an operator so that the orthogonal state can beobtained (steps S103 and S104), and this operation is repeated until theorthogonal state is obtained (step S105).

After the orthogonal state is obtained, the tip coordinate is checkedfor displacement (step S106).

When displacement occurs, the sequence returns to the step S102 so thatthe tip coordinate is moved. After the tip coordinate is moved, in orderto obtain the orthogonal state again, the attitude axis 52 and therotational axis 54 are rotated. Namely, the steps S102 through S106 arerepeated. Similarly, at the time of teaching from the teaching point P₂on the 45 degrees slanted surface to the teaching point P₃ on theupright surface, the steps S102 through S106 are repeated.

When the program creation by the teaching operation of the attitudechange corner section is completed, thereafter the working axis is movedto a teaching point by pushing down the Working axis feed key of theteaching box, or using the handle or the joy stick and the teaching ismade so that the respective teaching points of the working program arecreated (step S107). However, if the teaching operation of the attitudechange corner section is to be performed, then the steps S102 throughS106 are executed. Finally, instructions such as shutter closing andprogram end of the auxiliary function code are given so that thecreation of the working program is ended.

In the teaching point check operation, if the attitude angles (=therotating angles of the rotational axis 52 and the attitude axis 54) areto be changed, it is necessary to readjust the attitude angles at theteaching points, and the attitude angles are corrected according to theabove procedure.

As mentioned above, in the working head of the three-dimensional laserworking machine having the head structure that the working points do notchange when the rotational axis and the attitude axis are rotated, whenthe attitude axis is rotated at the time of teaching, the orthogonalstate is broken. For this reason, the operator rotates the rotationalaxis according to the movement of the attitude axis so as to obtain theorthogonal state. However, with this, since the orthogonal state shouldbe made for each of the teaching points, as a number of the teachingpoints increases, the teaching takes longer time. Furthermore, if theattitude direction is to be corrected, then there arises a problem thatthe rotating angles of the rotational axis and the attitude axis shouldbe corrected.

It is an object of the present invention to provide a control apparatusfor a three-dimensional laser working machine which is capable of makingteaching which maintains an orthogonal state of a laser nozzle withrespect to a working surface efficiently and fast in a three-dimensionallaser working machine having a head structure that working points do notchange when a rotational axis and an attitude axis are rotated.

DISCLOSURE OF THE INVENTION

The control apparatus according to the present invention controls athree-dimensional laser working machine. The three-dimensional laserworking machine includes a head structure that working points do notchange when a rotational axis and an attitude axis are rotated. Thecontrol apparatus decides a tip position and an attitude of a nozzle ofthe head structure and carries out working based on the decided tipposition. This control apparatus comprises a unit which calculates anozzle direction vector from current angles of the rotational axis andthe attitude axis, a unit which calculates an angle where the attitudeaxis changes for constant time and calculating an angle through whichthe rotational axis is rotated so that X and Y directions of the nozzledirection vector are kept constant according to an angle change amountof the attitude axis, and a unit which controls the rotation of therotational axis by the calculated angle. Therefore, the rotational axiscan be rotated by the angle which is calculated so that the X and Ydirections of the nozzle direction vector are kept constant according toa constant time angle change amount of the attitude axis, and the X andY directions of the nozzle direction vector can be kept constant.

In the above-mentioned control apparatus, when teaching new teachingpoint accompanying the rotation of the attitude axis from a teachingpoint of an orthogonal state, the rotation of the rotational axis iscontrolled according to the change amount of the attitude axis so thatthe orthogonal state with respect to a workpiece is obtained. Therefore,the rotational axis can be rotated by the angle which is calculated sothat the X and Y directions of the nozzle direction vector are keptconstant according to a constant time angle change amount of theattitude axis, and the X and Y directions of the nozzle direction vectorcan be kept constantly in a direction which is orthogonal to theworkpiece.

In the above-mentioned control apparatus, when the attitude axis isrotated in order to correct an attitude direction with respect to theteaching point once created, the rotation of the rotational axis iscontrolled so that the orthogonal state is obtained with respect to theworkpiece according to the change amount of the attitude axis.Therefore, also when the attitude axis is rotated from the orthogonalstate at the time of correcting the teaching, the rotational axis can berotated so as to be kept orthogonal to a working workpiece according tothe constant time angle change amount of the attitude axis.

In the above-mentioned control apparatus, constant movement of thenozzle direction vector can be switched between valid and invalid, andwhen movement instructions such as jog and fast-forward of the attitudeaxis are given, the rotation of the rotational axis is controlled by thecalculated angle so that X and Y directions of the nozzle directionvector are kept constant according to the change amount of the attitudeaxis. Therefore, constant movement of the nozzle direction vector can beswitched between valid and invalid, and the switching between valid andinvalid is always possible during the teaching operation, the operationof the control apparatus and the like. Further, when movementinstructions such as jog and fast-forward are given to the attitudeaxis, since the rotational axis is rotated by the angle which iscalculated so that the X and Y directions of the nozzle direction vectorare kept constant according to the constant time angle change amount ofthe attitude axis, the operation for obtaining the orthogonal state canbe omitted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a structural example of athree-dimensional laser working machine to which a control apparatus ofthe present invention is applied;

FIG. 2 is a schematic diagram showing a structure of a working head ofthe three-dimensional laser working machine to which the controlapparatus of the present invention is applied;

FIG. 3 is a block diagram showing the control apparatus for athree-dimensional laser working machine according to one embodiment ofthe present invention;

FIG. 4 is a flowchart showing a teaching process by means of the controlapparatus for a three-dimensional laser working machine of the presentinvention;

FIG. 5 is a graph showing a locus of a nozzle direction vector on X andY planes and an angle change of a rotational axis and an attitude axisof the working head;

FIG. 6 is a schematic diagram showing a structure of the working head tobe used in the three-dimensional laser working machine;

FIG. 7 is a perspective view showing an outline of an attitude change ofthe working head at an attitude change corner section; and

FIG. 8 is a flowchart showing a teaching operation by means of aconventional control apparatus for a three-dimensional laser workingmachine.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the control apparatus for a three-dimensional laserworking machine according to the present invention will be explained indetail below with reference to the accompanying drawings.

FIG. 1 shows a structural example of a three-dimensional laser workingmachine to which a control apparatus of the present invention isapplied. This three-dimensional laser working machine has a work table 2which is provided on a head 1 so as to be capable of moving in an Xaxial direction, a cross rail 6 which is horizontally laid across rightand left columns 4 and 5, a Y axial unit 7 which is provided on thecross rail 6 so as to be capable of moving in a Y axial direction, a Zaxial unit 8 which is provided to the Y axial unit 7 so as to be capableof moving in a Z axial direction, a working head 9 which is attached tothe Z axial unit 8, a laser nozzle (working nozzle) 10 which is providedto a tip portion of the working head 9, a computer-type numerical valuecontrol unit 11, and a pendant type teaching box 12. The numerical valuecontrol unit 11 has an operation board 11A and an image display section11B such as CRT as man-machine interface.

The work table 2, the Y axial unit 7 and the Z axial unit 8 are drivenby an X axial servomotor, a Y axial servomotor and a Z axial servomotor,not shown, respectively, and their positions are controlled by axialinstructions of the numerical value control unit 11.

The working head 9 is constituted similarly to the conventional one, andas shown in FIG. 2, it has a rotational axis 14 which is provided to atip of the Z axis unit 8 by a bearing member 13 so as to be rotatablearound a center axis of the Z axis, and an attitude axis 16 which isattached to a tip of the rotational axis 14 by a bearing member 15 so asto be rotatable around an axis slanted with respect to the Z axis. Thelaser nozzle 10 is attached to a tip of the attitude axis 16. Therotational axis 14 is driven to be rotated by an a axial servomotor 17,and the attitude axis 16 is driven to be rotated by a β axial servomotor18.

The X axial servomotor, the Y axial servomotor and the Z axialservomotor (not shown), the a axial servomotor 17 and the β axialservomotor 18 are driven by a driving signal from the numerical valuecontrol unit 11, and are controlled so that while a separate distance ofthe laser nozzle 10 from a workpiece on the work table 2 is being keptconstant according to teaching data, a spot of a laser beam follows aperiphery of a working line and a direction attitude of the laser nozzle10 is vertical (normal) to the surface of a workpiece W.

FIG. 3 shows an optical system of the above-mentioned three-dimensionallaser working machine and a control system including the controlapparatus for a three-dimensional laser working machine of the presentinvention. In FIG. 3, parts such as the work table 2, the Y axial unit 7and the Z axial unit 8 are totally called as a working machine main body20. The three-dimensional laser working machine has a laser oscillator21 as the optical system, and a laser beam B output from the laseroscillator 21 reaches the laser nozzle 10 via the working head 9 and isemitted to a surface of the workpiece W to be worked by the laser nozzle10.

The control apparatus for a three-dimensional laser working machine hasa nozzle direction vector operation/storage section 30, a rotating anglecalculating section 31 and a rotational axis operation control section32.

The nozzle direction vector operation/storage section 30 is operatedwhen validity of nozzle direction vector constant movement is turned onby the teaching box 12 or by handle and joy stick provided to theoperation board 11A, and calculates a nozzle direction vector from thecurrent rotating angles of the rotational axis 14 and the attitude axis16 and stores it.

The rotating angle calculating section 31 obtains an angle through whichthe attitude axis 16 was rotated for constant time by instructions fromthe teaching box 12, the handle and joy stick provided to the operationboard 11A and the numerical value control unit 11, and calculates anangle through which the rotational axis 14 is to be rotated so that Xand Y directions of the nozzle direction vector calculated by the nozzledirection vector operation/storage section 30 are kept constantaccording to a change amount of the attitude axis 16.

The rotational axis operation control section 32 controls the rotationof the rotational axis 14 based on the rotating angle of the rotationalaxis 14 calculated by the rotating angle calculating section 31.

Next, there will be explained below the teaching of the attitude changecorner section by means of the control apparatus for a three-dimensionallaser working machine having the above structure with reference to FIG.4.

Firstly, various settings of the teaching box are carried out, and theteaching operation for teaching working points is brought into astartable state by using a working machine (step S1).

Next, an instruction such as shutter opening of an auxiliary functioncode as the initial setting in the working program is given, and aworking axis is moved to a teaching point by pushing down a working axisfeed key provided to the teaching box or using the handle or the joystick and teaching is made so that respective teaching points in theworking program are created (step S2).

When the teaching points are created, in the conventional teachingoperation of the attitude change corner section, for example in the caseof the teaching from the teaching point P₁ on the horizontal surface tothe teaching point P₂ on the 45 degrees slanted surface shown in FIG. 7,the working head 9 is moved so that the tip coordinate meets theteaching point P₂ on the 45 degrees slanted surface (step S3).

Since the nozzle direction vector constant movement is switching intovalid and the attitude axis 16 as well as the rotational axis 14 ismoved so that the X and Y directions of the nozzle direction vector arekept constant according to a constant time angle change amount of theattitude axis 16, the attitude axis 16 is moved until the orthogonalstate is obtained (step S4).

Thereafter, the tip coordinate is checked for displacement (step S5).When displacement occurs, the sequence returns to step S3 so that thetip coordinate is moved. After the tip coordinate is moved, the processat step S4 is executed so that the orthogonal state is again obtained.Namely, the steps S3 through S5 are repeated.

Similarly, at the time of the teaching from the teaching point P₂ on the45 degrees slanted surface to the teaching point on the upright surfaceshown in FIG. 7, steps S3 through S5 are repeated.

When the program creation by the teaching of the attitude change cornersection is completed, the working point is moved to a teaching point bypushing down the working axis feed key provided to the teaching box 12or using the handle or the joy stick and the teaching is made so thatthe respective teaching points in the working program are created (stepS6). However, when there is the teaching of the attitude change cornersection, steps S3 through S5 are executed. Finally, instructions such asshutter closing and program end of the auxiliary function code are givenso that the creation of the working program is ended.

In the operation process in the rotating angle calculating section 31,calculation is made by the following logical expression. FIG. 5 shows alocus of the nozzle direction vector with respect to a change of theattitude axis 16 on X and Y planes. In FIG. 5, A is a locus of thenozzle direction vector with respect to a change of the attitude axis16, θr is a current attitude axis angle, Nr is a point on the locus A atthe attitude axis angle θr, La is a straight line made by the point Nron the locus A and an original point, θx is an angle made by thestraight line La and the X axis, Δθ is a constant time angle changeamount of the attitude axis 16, Δθ is a point on the locus A in theangle change amount Δθ, ΔLas a straight line made by the point ΔN andthe original point, Δ θx is an angle made by the straight line ΔLa andthe X axis, and θ* is an angle change amount of the rotational axis 14for keeping the nozzle direction constant according to the constant timeangle change amount of the attitude axis 16.

When the angle of the rotational axis 14 of the working head 9 is α andthe angle of the attitude axis 16 is β, a nozzle direction unitdirection vector d becomes: $d = \begin{bmatrix}{{{{{- 1}/2} \cdot \cos}\quad \alpha} + {{{1/2} \cdot \cos}\quad {\alpha \cdot \cos}\quad \beta} - {{{\sqrt{2}/2} \cdot \sin}\quad {\alpha \cdot \sin}\quad \beta}} \\{{{{1/2} \cdot \sin}\quad \alpha} - {{{1/2} \cdot \sin}\quad {\alpha \cdot \cos}\quad \beta} - {{{\sqrt{2}/2} \cdot \cos}\quad {\alpha \cdot \sin}\quad \beta}} \\{{{- 1}/2} - {{{1/2} \cdot \cos}\quad \beta}}\end{bmatrix}$

At this time, if the attitude axis 16 is 0 degrees, X and Y aresimplified as follows,

X=1/2·cosβ−1/2

Y=−2/2·sinβ

When the above equations are drawn on the X and Y planes, the locus A isobtained. When the angle formed by the straight line La and the X lineat the point Nr is θx, a tilt of the straight line La is represented bythe following equation,

tan θx=Y/X

=−2·sin β/(cos β−1)

Therefore, the angle θx made by the straight line La and the X axis atthe point Nr becomes,

θx=tan⁻¹{−2·sin β/(cos β−1)}

When the angle made by the straight line ΔLa and the X line with respectto the angle change amount Δθ is Δθx, it becomes,

Δθx=tan⁻¹{−2·sin(β+Δβ)/(cos (β+Δβ)−1)}

At this time, in order to keep the X and Y directions of the nozzledirection vector constant, the straight line La before the angle of theattitude axis 16 changes may match with the straight lineΔLa after theangle changes. For this reason, a displaced angle may be rotated throughthe rotational axis 14, and thus a correcting angle θ* of the rotationalaxis can be deduced according to the following calculation equation.

θ*=θx−Δθx

When this is represented sequentially, this becomes,

θxn=tan⁻¹(−2·sin(βn−1+Δβ)/cos(βn−1+Δβ)−1))

and a correcting angle 22 of the rotational axis by means of thesequential expression is deduced from the following calculationequation,

θ*n=θxn−θxn−1

As mentioned above, the nozzle-direction vector is calculated from thecurrent angle of the rotational axis 14 and current angle of theattitude axis 16, and the rotational axis 14 is rotated through an anglewhich is calculated so that the X and Y directions of the nozzledirection vector are kept constant according to the constant time anglechange amount of the attitude axis 16. For this reason, the operationfor obtaining the orthogonal state becomes easy, and the operability dueto shortening of time can be improved.

In addition, when the attitude axis is rotated from the orthogonal stateat the time of correcting the teaching, the rotational axis is rotatedso as to be kept in the orthogonal state with respect to a workingworkpiece according to the constant time angle change amount of theattitude axis. For this reason, the operation for obtaining theorthogonal state can be omitted, and the operability due to theshortening of time can be improved.

In addition, since the constant movement of the nozzle direction vectorcan be switched between valid and invalid, the switching between validand invalid is always possible for example during the teaching operationor operation of the control apparatus. Further, when moving instructionssuch as jog or fast-forward are given to the attitude axis, therotational axis is rotated through an angle which is calculated so thatthe X and Y directions of the nozzle direction vector are kept constantaccording to the constant time angle change amount of the attitude axis.For this reason, the operation for obtaining the orthogonal state can beomitted, and the operability due to shortening of time can be improved.

INDUSTRIAL APPLICABILITY

The present invention can be used in a three-dimensional laser workingmachine which teaches a tip position and an attitude of a nozzle andcarries out working based on the teaching such as a three-dimensionallaser working machine for creating a die and the like.

What is claimed is:
 1. A control apparatus for a three-dimensional laserworking machine, said three-dimensional laser working machine includinga head structure for which working points do not change when arotational axis and an attitude axis are rotated, said control apparatusdeciding a tip position and an attitude of a nozzle of said headstructure and carrying out working based on the decided tip position,said control apparatus comprising: a unit which calculates a nozzledirection vector from current angles of the rotational axis and theattitude axis, a unit which calculates an angle where the attitude axischanges for constant time and calculating an angle through which therotational axis is rotated so that X and Y directions of the nozzledirection vector are kept constant according to an angle change amountof the attitude axis, and a unit which controls the rotation of therotational axis based on the calculated angle.
 2. The control apparatusfor a three-dimensional laser working machine according to claim 1,wherein, when teaching of new teaching point accompanying the rotationof the attitude axis from a teaching point of an orthogonal state, therotation of the rotational axis is controlled so that the orthogonalstate with respect to a workpiece is obtained according to the changeamount of the attitude axis.
 3. The control apparatus for athree-dimensional laser working machine according to claim 2, wherein,when the attitude axis is rotated in order to correct an attitudedirection with respect to the teaching point once created, the rotationof the rotational axis is controlled so that the orthogonal state isobtained with respect to the workpiece according to the change amount ofthe attitude axis.
 4. The control apparatus for a three-dimensionallaser working machine according to claim 1, wherein, constant movementof the nozzle direction vector can be switched between valid andinvalid, and when movement instructions such as jog and fast-forward ofthe attitude axis are given, the rotation of the rotational axis iscontrolled by the calculated angle so that X and Y directions of thenozzle direction vector are kept constant according to the change amountof the attitude axis.
 5. A control apparatus for controlling athree-dimensional laser working machine that includes a head structurehaving a nozzle, and capable of preventing working points from shiftingwhen a rotational axis and an attitude axis are rotated, the controlapparatus determining a tip position and an attitude of the nozzle by ateaching operation and carrying out work based on the determined tipposition, the control apparatus comprising: a unit that calculates anozzle direction vector from current angles of the rotational axis andthe attitude axis at a teaching point; a unit that calculates avariation of an angle in the attitude axis between its value at teachingpoints and an amount of an angle for the rotational axis to be rotatedat the teaching point so that X and Y directions of the nozzle directionvector are kept constant according to the variation of the angle in theattitude axis; and a unit that controls the rotation of the rotationalaxis based on the amount of the angle calculated, wherein when theteaching point is moved to a new teaching point accompanying a rotationof the attitude axis from the previous teaching point, the rotation ofthe rotational axis is controlled so that a positionally orthogonalrelationship between the nozzle and a workpiece is maintained accordingto the amount of the angle calculated.
 6. The control apparatus for athree-dimensional laser working machine according to claim 5, whereinwhen the attitude axis is rotated in order to correct an attitudedirection with respect to the previous teaching point, the rotation axisis controlled so that the positionally orthogonal relationship betweenthe nozzle and the workpiece is maintained according to the changeamount of the angle calculated.
 7. A three-dimensional laser workingmachine, comprising; an oscillator that oscillates a laser beam; aworking head that transmits the laser beam to a workpiece and has arotational axis and an attitude axis; and the control apparatusaccording to claim 1 that controls the oscillator and the working head.